Month: August 2012

So as part of my renewal projects and drive I have been focused and interested in Biogas, in particular gas produced from the breakdown of wood at high temperature with limited oxygen.

After my experiments and success with making a biodiesel reactor and running a car off biodiesel for many years I had felt that this project fitted the natural progression. If I could make a fuel for diesel engines making a fuel for spark based engines was the alternative.

Before starting on this project I did a lot of research online.

YouTube was a fantastic resource that allowed me to see other peoples success but also how their projects have come together and the pitfalls they encountered.

BBC’s Bang goes the theory did an experiment where they used coffee grounds in a similar fashion, the link can be found here.

Another site I made extensive use of was MD Pub’s Gasifier, his research, experiments and documentation became the grounds for my own jumping off points.

So what is a Gasifier?

A Gasifier is a combustion chamber where organic substances (wood, coffee grounds or other organic substances) are burnt at high temperature with limited oxygen, this causes the organic and volatile compounds to separate. In principle it goes like this:

The wood (or organic substance) becomes unstable and breaks down into less complex substances – otherwise known as Pyrolysis (Wikipedia Link).

Once this process has happened the gas is in a raw and almost ‘dirty’ state, at such a high temperature it contains moisture and tars that were not thermally broken down, before it can be used in any combustion engine the gas must be cleaned and impurities removed.

I have broken my project up in to two sections.

Gas production device

Gas cleaning device

This post focuses on Part 1, the manufacture of a BioGas production system.

From the research I did, it seems the most successful projects were ones that used compressed air, injected into the combustion chamber at the hottest point. I chose to make a ‘injection ring’ where 5 copper pipes inject air into a steel cylinder. To get started I needed a base:

Using an old 25 litre chemical drum, I cut the top off, leaving the pressed steel rim intact, This gave me a large working area to easily fit parts and get my hands into areas needed for screwing / working. For my combustion chamber I found compliments of eBay an old fire extinguisher – yes I’m aware of the irony.

I cut the base off the extinguisher:

and removed the razor sharp edge left by the cutting tool:

You can see from the positioning the plan, filling the now top of the chamber with the reaction occurring at the neck with the gas and ash flowing out of the bottom.

The next step was to drill holes and fit the air injection pipes. The drilling of the holes and fitting of the pipes was very simple, with a small jig setup to prevent the drill from travelling on a circular edge. Once I had the pipes fitted I made a ring of copper pipe around the outside and connected all the injection tubes to the ring. This gave me a single point where I could connect an air hose and apply compressed air.

From some of the learning’s from MD Pub’s pages, he had major trouble with gas tar and water escaping from the gaps between the pipe and the cylinder. So I decided before moving on that I would seal the pipes to the cylinder. My original idea was to weld or braze the gap, but after watching numerous videos on how to braze and following the pack instructions to the letter, I was unable to form a solid bond that couldn’t be chipped off with a finger nail – see photo

So my next idea was to use chemical metal. A two part compound that when combined becomes tough and bonds metal together. Fab I thought. After cleaning the remains of brazing rods off the copper and steel I set about trying to glue the gaps up. What a success! The glue set, didn’t shrink and all the gaps were filled. All my problems were solved – or so I thought!

I left the project for a week or so, coming back everything looked good, the glue hadn’t fallen off and holding the base up to the light resulted in no pin pricks of light shining through. Then I dropped it (the fire extinguisher) and the glue shattered. Being so brittle and so inflexible all of the joints immediately failed I needed a better idea, a more flexible idea.. Re-reading MD Pub’s pages he talked about using a flexible high temperature silicon sealer to fill in all the gaps. So a quick trip down the local hardware store saw me back in business.

After sealing all the gaps and joints I moved onto making a lid, making friends with a local metal workshop I had a rummage around the offcuts bin and found a sheet of metal that would be perfect. Cutting a doughnut shaped ring out from the metal and fitting it too the inverted fire extinguisher with a little silicone seal in place around the gaps:

Fab! So now I have fitted my chamber up, secured a constant stream of compressed air for the reaction to occur. All that was next was to test my Gasifier.

Loading up my reaction chamber with wood and charcoal I sealed the chamber (with the now lid, ex base of the fire extinguisher). Once the airline was attached and a constant stream of air was being forced into the chamber I felt the Gasifier immediately heat up, plenty of smoke was being product from the exit port but nothing flammable. This went on for 20 minutes and as the temperature increased so did the quantity of non-flammable gas being produced. Sadly the seal of the combustion chamber failed soon after, resulting in a small fireball about the size of a football coming out from the combustion chamber. This has shown me two things, One: Gas was being produced, Two: I need a better seal on my gas chamber.

My plan for the rest of this project is to find / design a better heat proof seal for the combustion chamber and to replicate the experiment. I believe I’m on the cusp of making this project work, so a few more steps particularly in the name of safety shouldn’t be a problem.

So I’ve discovered that after formatting some SD Cards for use with some ARM based devices means that the card is left unformattable and unable to be read or reused. Whenever I went too format the card using Windows Disk Utiltity or Mac Disk Utility it would fail and tell me the media was not ready. Futher investigation let me to discovered that some of the images I was using start writing the image to the file at 8 or 16 bytes, leaving the 1st sector unformatted with the uboot image.

Greetings! To a new and updated website!
This website is the new and much needed refresh to the Mathew Jenkinson Dot Co Do UK webspace. It brings new features such as updates via my mobile phone, tagging, rss and photo galleries. This new exciting roll out makes use of wordpress as the core frame work and represents a shift in focus from my writing of code & showcasing of technical websites to my presenting of projects, ideas and achievements.

To give you a bit of history from now (7th Aug 2012) I (along with some others) participated in Oxfams Trailwalker – a 100KM trek starting from portsmouth and finishing in Brighton along the south downs way. This walk was indeed epic and by the end of the walk we were all truely broken. The blog for the walk can be found at: